I'm sorry you had to go through that- here are some tips...
1. Never try and restrict them in any way while they are shaking.
2. Try to protect them and make sure they don't injure themselves further. Remove any hard objects around them.
3. Never insert anything into their mouth- they might choke on it.
4. After the seizure subsides, roll them to their side.
5. Talk to the person gently and try to re-orient them. They might be out of it and confused so try and let them know where they are/time/date/ etc.
6. Call for medical assistance if needed.